lumia

[samy saifi]

I have Nokia Lumia 1520 and updated it to win 10 what will happen if i reset my phone will it go back to win8.1

 

[xandros9]

Moved to W10M.

If you factory reset any Windows Phone, it stays on the last OS version it had installed. So no, it won't.

Now if you use a tool like Windows Device Recovery Tool which wipes the phone entirely and installs a downloaded file, that is the method to revert to 8.1.